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https://issues.apache.org/jira/browse/FLINK-18196?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17213757#comment-17213757
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Kai Chen commented on FLINK-18196:
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hi [~pnowojski] [~roman_khachatryan] ，it's true that upgrading JDK version can
fix this NPE and i agree that this must be some weird JDK bug. However
upgrating JDK version is a big work in production cluster. So i offered this
patch for the ones who meet the same problem with me.
I didn't dig into this JDK bug. I was confused with this NPE at first .Then i
debugged and found the ‘checkpointMetaData’ probably be swept by gc(which
should not happen). I tried to create a new CheckpointMetaData in the MailBox
lambda expression to avoid it and it worked! I‘m looking forward to learning
the root cause.
> flink throws `NullPointerException` when executeCheckpointing
> -------------------------------------------------------------
>
> Key: FLINK-18196
> URL: https://issues.apache.org/jira/browse/FLINK-18196
> Project: Flink
> Issue Type: Bug
> Components: Runtime / Checkpointing
> Affects Versions: 1.10.0, 1.10.1
> Environment: flink version: flink-1.10.0 flink-1.10.1
> jdk version: jdk1.8.0_40
> Reporter: Kai Chen
> Priority: Major
> Fix For: 1.12.0, 1.10.3, 1.11.3
>
>
> I meet checkpoint NPE when executing wordcount example:
> java.lang.Exception: Could not perform checkpoint 5505 for operator Source:
> KafkaTableSource(xxx) > SourceConversion(table=[xxx, source:
> [KafkaTableSource(xxx)]], fields=[xxx]) > Calc(select=[xxx) AS xxx]) >
> SinkConversionToTuple2 -- > Sink: Elasticsearch6UpsertTableSink(xxx) (1/1).
> at
> org.apache.flink.streaming.runtime.tasks.StreamTask.triggerCheckpoint(StreamTask.java:802)
> at
> org.apache.flink.streaming.runtime.tasks.StreamTask.lambda$triggerCheckpointAsync$3(StreamTask.java:777)
> at
> org.apache.flink.streaming.runtime.tasks.StreamTask$$Lambda$228/1024478318.call(Unknown
> Source)
> at java.util.concurrent.FutureTask.run(FutureTask.java:266)
> at
> org.apache.flink.streaming.runtime.tasks.StreamTaskActionExecutor$SynchronizedStreamTaskActionExecutor.run(StreamTaskActionExecutor.java:87)
> at org.apache.flink.streaming.runtime.tasks.mailbox.Mail.run(Mail.java:78)
> at
> org.apache.flink.streaming.runtime.tasks.mailbox.MailboxProcessor.processMail(MailboxProcessor.java:261)
> at
> org.apache.flink.streaming.runtime.tasks.mailbox.MailboxProcessor.runMailboxLoop(MailboxProcessor.java:186)
> at
> org.apache.flink.streaming.runtime.tasks.StreamTask.runMailboxLoop(StreamTask.java:487)
> at
> org.apache.flink.streaming.runtime.tasks.StreamTask.invoke(StreamTask.java:470)
> at org.apache.flink.runtime.taskmanager.Task.doRun(Task.java:707)
> at org.apache.flink.runtime.taskmanager.Task.run(Task.java:532)
> at java.lang.Thread.run(Thread.java:745)
> Caused by: java.lang.NullPointerException
> at
> org.apache.flink.streaming.runtime.tasks.StreamTask$CheckpointingOperation.executeCheckpointing(StreamTask.java:1411)
> at
> org.apache.flink.streaming.runtime.tasks.StreamTask.checkpointState(StreamTask.java:991)
> at
> org.apache.flink.streaming.runtime.tasks.StreamTask.lambda$performCheckpoint$5(StreamTask.java:887)
> at
> org.apache.flink.streaming.runtime.tasks.StreamTask$$Lambda$229/1010499540.run(Unknown
> Source)
> at
> org.apache.flink.streaming.runtime.tasks.StreamTaskActionExecutor$SynchronizedStreamTaskActionExecutor.runThrowing(StreamTaskActionExecutor.java:94)
> at
> org.apache.flink.streaming.runtime.tasks.StreamTask.performCheckpoint(StreamTask.java:860)
> at
> org.apache.flink.streaming.runtime.tasks.StreamTask.triggerCheckpoint(StreamTask.java:793)
> ... 12 more
>
> checkpoint configuration
> |Checkpointing Mode|Exactly Once|
> |Interval|5s|
> |Timeout|10m 0s|
> |Minimum Pause Between Checkpoints|0ms|
> |Maximum Concurrent Checkpoints|1|
> With debug enabled, I found `checkpointMetaData` is null at
>
> [https://github.com/apache/flink/blob/release-1.10.0/flink-streaming-java/src/main/java/org/apache/flink/streaming/runtime/tasks/StreamTask.java#L1421]
>
> I fixed this with this patch:
> [https://github.com/yuchuanchen/flink/commit/e5122d9787be1fee9bce141887e0d70c9b0a4f19]
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